Three decades after federal courts began ordering cities to mix their classrooms racially, the pendulum has begun to swing the other direction. A growing number of cities are dismantling their busing programs. Today, St. Louis votes on a sales-tax increase that, if approved, would bring it closer to ending 27 years of court jurisdiction over its schools.

Although backers and critics of desegregation disagree on almost everything, they share common ground on this: The racial mixing of schoolchildren has so far failed to alleviate America's long-standing challenges with race relations, urban poverty, and minority underachievement. Integration has been overwhelmed by stronger forces, such as family circumstances and the changing racial composition of inner cities.

In any case, the United States should get its answer soon. While cities from Austin, Texas, to Boston are moving back to neighborhood schools, St. Louis is trying to keep desegregation alive, busing minority students not only within the city but also out to the suburbs. Under the proposed settlement, which faces the crucial tax vote today, all but one of the area's school districts would continue accepting students for at least the next three years.

St. Louis is a key test case of whether voluntary desegregation can survive after pressure applied by the courts disappears. "Compared to other desegregation cases that are being dismantled, there's some effort in St. Louis to keep the program alive," says Amy Stuart Wells, education professor at the University of California at Los Angeles, who has studied St. Louis's busing program.

Many cities are moving away from the goal of integration some 30 years after the US embarked on its huge social experiment. In the mid-1960s, for example, only about 12 percent of African-American students attended desegregated schools. By 1972, the figure had jumped to 44 percent.

But by the 1990s the pendulum had begun swinging back. According to the Harvard Project on School Desegregation, 20 states saw an increase in the percentage of African-American students attending segregated schools between 1989 and 1994, while only 13 experienced a decrease. (The rest either saw no change or had insufficient data.)

The changes were mostly small, but they represent a dramatic shift, researchers say.

"It's a very, very important kind of historic change," says Gary Orfield, director of the Harvard Project. Schools are "resegregating faster than at any time since the Brown decision," the landmark 1954 Supreme Court ruling that ignited the desegregation movement.

The high court is also setting the new direction. In three decisions this decade, it has paved the way for school districts to get out from under judicial oversight in return for good-faith efforts to desegregate. Denver, Dallas, Buffalo, N.Y., and Savannah, Ga., got their desegregation orders lifted and have been joined by a growing slate of other cities, such as Indianapolis, Austin, and Nashville, Tenn. More are expected to do the same.

Surprisingly, such moves have faced little local opposition. One reason: Civil-rights groups are besieged on many fronts and can't concentrate solely on school desegregation. "In many respects, the energy's not there to start the movement again," says Charles Willie, a desegregation consultant and sociologist at Harvard.

Changing demographics also play a role. When busing was implemented, supporters argued the only way to give minorities an equal education was to send them to white schools, which had more resources than did minority schools. But cities have changed a lot in 30 years, in some cases rendering desegregation moot.

Take Boston, for example. Some of the neighborhoods that fought busing in the 1970s have become much more diverse themselves. Minorities now make up one-quarter of formerly all-white East Boston, one-third of South Boston, and just over half of Charlestown. In the city as a whole, minorities represent 84 percent of public-school pupils -so there's little left to integrate.

ALL these forces are reshaping public attitudes, creating more emphasis on school quality. "The issue of achievement is outweighing the issue of where children are going to school," says LaMar Miller of the Metropolitan Center for Urban Education at New York University.

The refocused emphasis on school quality is evident in St. Louis - among both supporters and opponents of desegregation.

"I would like to see black children get a better education, but it's their parents' responsibility and their responsibility," says John Stoeffler of the National Association for Neighborhood Schools of Eastern Missouri. "Education begins in the heart and in the heart of the home.... It's not going to be solved by the courts." His answer: Scrap busing in favor of neighborhood schools.

"For whatever reasons, the city school systems ... have not been particularly successful," says Bruce La Pierre, the court-appointed special master who negotiated St. Louis's 1983 desegregation settlement. His answer: Keep city-suburb busing alive because minorities get a better education at suburban schools.

There's some evidence to back him up. Some 77 percent of city students bused to the suburbs go on to college - much higher than the 55 percent statewide average for African-Americans.

On the other hand, only a small share of city students - about 13,000 - go to suburban schools. Many more minority students attend city schools that are not keeping academic pace with white schools in the suburbs.

Should cities or the US come up with a new remedy?

Already, young African-Americans graduate from high school almost as frequently as their white counterparts do: 86.2 percent to 87.6 percent. College graduation rates are up, too.

Nevertheless, blacks are still three times more likely to be poor than whites are (the same ratio as in 1959). Schools where the student body is mostly black or Latino are 16 times more likely to have concentrated poverty than are white schools.

"The effect of desegregation on education isn't huge," concedes Professor Orfield, a desegregation proponent. "But to bet on segregation is really, truly a reckless bet. It's a bet that has never won."